Development of Mid-Infrared Light Emitting Diodes to Replace Incandescent Airfield Lighting ...

191 Pages·2017·18.24 MB·English

Development of Mid-Infrared Light Emitting Diodes to
Replace Incandescent Airfield Lighting
Jonathan Paul Hayton
MPhys (Hons.)
This thesis is submitted in fulfilment of the requirements for the degree of
Doctor of Philosophy
Department of Physics
Lancaster University
United Kingdom
October 2016
This project was supported by the Centre for Global Eco-Innovation and is part
financed by the European Regional Development Fund.
www.cgeinnovation.org
Development of Mid-Infrared Light Emitting Diodes to
Replace Incandescent Airfield Lighting
Jonathan Paul Hayton
MPhys (Hons.)
October 2016
Abstract
Thisworkstudiedthereplacementofincandescentairfieldlightingsystemswith
light emitting diodes. The focus was on the replacement of the infrared component
of the incandescent spectra. A series of LEDs with a variety of nanostructures in
different material systems were produced and tested to determine their suitability
in replacing incandescent airfield lighting systems.
Utilising quantum dashes in the active region, a surface emitting LED achieved
an output power of 1.2mW at 1.97µm. This device had a wall-plug efficiency of
0.7%, an efficiency greater than that obtained in comparable commercially avail-
able surface emitting devices. The output power of this device was limited by the
confinement of electrons within the quantum dashes at room temperature.
Another device characterised in this study was an LED with sub-monolayer
InSb/GaSb quantum dots in the active region. The sub-monolayer InSb quantum
dots were grown at Lancaster on GaSb substrates using molecular beam epitaxy
and fabricated into surface emitting LEDs. These were investigated using x-ray
diffraction, transmission electron microscopy and electroluminescence. This is the
first reported electroluminescence from such devices. Emission was measured at
temperatures up to 250K. Room temperature emission was from the quantum
wells in which the quantum dots where grown, output power was 80µW at a
wavelength of 1.66µm.
Further devices with InSb sub-monolayer insertions were fabricated into edge
emittingdiodes. ThesesamplesweregrownonGaAsusinginterfacialmisfitarrays,
defect densities were reduced through the use of defect filtering layers. The thread-
ing dislocation density decreased by a factor of 6 from 2.5×109/cm2 to 4×108/cm2
between the bottom and top of the defect filtering layer. The edge emitting de-
vices achieved lasing up to 200K with a characteristic temperature of 150K. These
devices were limited by Shockley–Read–Hall recombination and weak confinement
of carriers within the InSb regions. The inclusion of AlGaSb barriers improved
room temperature operation with output power increasing from 2µW to 42µW.
In addition, increased confinement also resulted in a decrease in peak wavelength
from 2.01µm to 1.81µm.
GaInSb quantum well samples were produced on GaAs substrates utilising an
interfacial misfit array. This included the first reported instances of ternary inter-
facial misfit array interfaces with threading dislocation densities of <2×109/cm2
for an AlGaSb/GaAs interface and 5×1010/cm2 for an InAlSb/GaAs interface. By
utilising an AlGaSb interfacial misfit array it was possible to improve the con-
finement of carriers within the GaInSb quantum wells, resulting in a twenty fold
increase in room temperature photoluminescence intensity.
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Declaration of Authorship
I,JonathanPaulHayton,declarethatthisthesistitled,‘DevelopmentofMid-Infrared
Light Emitting Diodes to Replace Incandescent Airfield Lighting’andtheworkpresented
in it are my own. I confirm that:
(cid:136) This work was done wholly or mainly while in candidature for a research degree
at Lancaster University.
(cid:136) Where I have consulted the published work of others, this is always clearly at-
tributed.
(cid:136) I have acknowledged all main sources of help.
(cid:136) No part of this has previously been or is being submitted to any other university
or other academic institution.
(cid:136) Where the thesis is based on work done by myself jointly with others, I have made
clear exactly what was done by others and what I have contributed myself.
Signed:
Date:
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Acknowledgements
Firstly I would like to thank my supervisor, Prof. Anthony Krier, for the support and
guidance he has given me during my studies.
I would also like to thank my examiners Dr Andy Marshall and Prof Mohamed
Henini.
I am also grateful to those within the department who assisted in the growth and
characterisation of my samples, namely, Dr Michael Thompson, Dr Peter Carrington,
Hiromi Fujita, Dr Adam Craig and Dr Kylie O’Shea.
Science is a collaborative endeavour and I would also like to thank those people from
different institutions who have offered their time, knowledge and facilities to provide
me with new insight into the work I have done. This included Dr Ken Kennedy and
Saurabh Kumar at Sheffield University, Prof. Stephen Sweeney and Dr Igor Marko at
the University of Surrey, and Dr Siddharth Joshi of the III-V Lab, France.
In the past four years I have been very lucky to occupy two great offices. My
thankstoKylieO’Shea,ClaireTinker-Mill,AlexRobson,SamHarrison,QiLu,Aiyeshah
Alhodaib, Chris Woodhead, Jonny Roberts, Alex Jones and Yasir Noori for making this
possible.
I have also benefited during my time in the department from excellent support
from the technical support staff. I would like to thank Stephen Holden, Shonah Ion,
Stephen Holt, Ashley Wilson, John Statter, Graham Chapman, Phelton Stephenson,
Robin Lewsey and Dr Kunal Lulla Ramrakhiyan.
I would also like to take this opportunity to thank Dr Russell Harvey for being a
fantastic boss during my work as a technician. I truly enjoyed supporting first year labs
and the challenges this entailed. I must also thank you for being so accommodating of
the needs of my research.
My work was supported by the Centre for Global Eco-Innovation and I would like
to thank all involved for their support during the project.
The support of my family has never wavered and for this I give them special thanks.
It has been a comfort to know you’ve always had an open door. It is from you that I
gained my questioning mind which has led me to where I am today.
In writing these acknowledgements you come to realise just how many people make
a PhD possible, to these people I am indebted, but none more so, than to Steph. This
journey has been one we have taken together and whilst it has certainly taken the path
less travelled the scenery on the way has been worth it. I only hope that I can be there
for you, as you have been for me these last few month giving me the occasional little
push up the hill.
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Publications
1. JP Hayton, ARJ Marshall, MD Thompson, and A Krier. Characterisation of
Ga In Sb quantum wells (x ∼0.3) grown on GaAs using AlGaSb interface misfit
1−x x
buffer. AIMS Materials Science 2(2): 86–96, 2015
2. Q Lu, Q Zhuang, JP Hayton, M Yin and A Krier. Gain and tuning characteristics
of mid-infrared InSb quantum dot diode lasers. Appl. Phys. Lett. 105: 031115,
2014
3. JP Hayton, PJ Carrington, H Fujita, A Krier. Electroluminescent properties of
sub-monolayerInSbquantumdotsgrownonGaSbbyMBE.–paperinpreparation.
Presentations
1. JP Hayton, ARJ Marshall, MJ Thompson, and A Krier. A Comparative Study
of GaInSb Quantum Wells Grown on GaSb and Interfacial Misfit GaAs. UK
Semiconductors 2014, Sheffield, UK. (Poster)
2. JP Hayton, ARJ Marshall, MJ Thompson, and A Krier. Thermal quenching of
Ga In Sb quantum wells (x ∼0.3) grown on GaAs using AlGaSb interface misfit
1−x x
buffer. UK Semiconductors 2015, Sheffield, UK. (Poster)
3. JP Hayton, ARJ Marshall, MJ Thompson, and A Krier. Characterisation of
Ga In Sbquantum wells LEDs(x ∼0.3)grownonGaAs usingAlGaSb interface
1−x x
misfit buffer. WOCSDICE 2015, Smolenice, Slovakia. (Talk)
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Contents
1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Background Theory 5
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Band Structure of Semiconductors . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Temperature Dependence of Band Structure . . . . . . . . . . . . . . . . . 8
2.4 Band Alignment at Heterojunctions . . . . . . . . . . . . . . . . . . . . . 9
2.5 Quantum Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.6 Density of States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.7 Recombination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.7.1 Shockley–Read–Hall(SRH) . . . . . . . . . . . . . . . . . . . . . . 17
2.7.2 Radiative Recombination . . . . . . . . . . . . . . . . . . . . . . . 17
2.7.3 Auger Recombination . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.7.4 Intervalence Band Absorption . . . . . . . . . . . . . . . . . . . . . 21
2.7.5 Surface Recombination . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.8 Light Emitting Diodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.8.1 Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.9 Strain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.9.1 Dislocations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
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2.9.2 Critical Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.9.3 Strain Induced Band Shift . . . . . . . . . . . . . . . . . . . . . . . 29
2.10 High Lattice Mismatch Growth . . . . . . . . . . . . . . . . . . . . . . . . 31
3 Literature Review 33
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2 Bulk Alloy LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.3 GaIn(As)Sb/(Al)GaSb Multi Quantum Wells . . . . . . . . . . . . . . . . 39
3.4 Quantum Well Cascade LEDs . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.5 InSb/GaSb Quantum Dots . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.6 Quantum Dashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.7 Metamorphic Epitaxy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4 Experimental Details 55
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.2 Molecular Beam Epitaxy (MBE) . . . . . . . . . . . . . . . . . . . . . . . 56
4.3 Structural Characterisation . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.3.1 High Resolution X-Ray Diffraction . . . . . . . . . . . . . . . . . . 59
4.4 Device Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.4.1 GaInSb Quantum Well LEDs . . . . . . . . . . . . . . . . . . . . . 62
4.4.2 InP Quantum Dash LEDs . . . . . . . . . . . . . . . . . . . . . . . 65
4.4.3 InSb SML Quantum Dot LEDs . . . . . . . . . . . . . . . . . . . . 65
4.5 Optical Characterisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.5.1 Photoluminescence . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.5.2 Electroluminescence . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.6 Electronic Characterisation Techniques . . . . . . . . . . . . . . . . . . . . 69
4.6.1 Current-Voltage (I–V) Characteristics . . . . . . . . . . . . . . . . 69
4.6.2 Transmission Line Method (TLM) . . . . . . . . . . . . . . . . . . 70
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5 Growth and Characterisation of GaInSb/(Al)GaSb Multiple Quantum
Wells 71
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.2 Quantum Well Design and MBE Growth . . . . . . . . . . . . . . . . . . . 72
5.3 InGaSb Quantum Wells Grown on GaSb and GaAs with Different Barrier
Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.3.1 X-ray Diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.3.2 Transmission Electron Microscopy . . . . . . . . . . . . . . . . . . 80
5.3.3 Photoluminesence . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.4 Improved AlGaSb IMF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.5 Growth of InGaSb Quantum Well LEDs . . . . . . . . . . . . . . . . . . . 90
5.5.1 Electrical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . 91
5.5.2 Electroluminesence . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5.6 Growth and Characterisation of GaAs/InAlSb IMF . . . . . . . . . . . . . 94
5.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6 Comparison of LEDs with Different Degrees of Quantum Confinement
Emitting at 2µm 99
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
6.2 GaInAsSb/AlGaAsSb Double Heterojunction LEDs . . . . . . . . . . . . 100
6.2.1 Current – Voltage Characteristics . . . . . . . . . . . . . . . . . . . 101
6.2.2 Electroluminescence . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6.2.3 Power and Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . 106
6.2.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
6.3 GaInSb/GaSb Quantum Wells . . . . . . . . . . . . . . . . . . . . . . . . 107
6.3.1 Current – Voltage Characteristics . . . . . . . . . . . . . . . . . . . 107
6.3.2 Electroluminescence . . . . . . . . . . . . . . . . . . . . . . . . . . 108
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6.3.3 Power and Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6.3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6.4 InAs Quantum Dashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
6.4.1 Current – Voltage Characteristics . . . . . . . . . . . . . . . . . . . 111
6.4.2 Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
6.4.3 Electroluminescence . . . . . . . . . . . . . . . . . . . . . . . . . . 113
6.4.4 Pressure Dependent Electroluminescence. . . . . . . . . . . . . . . 117
6.4.5 Power and Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . 119
6.4.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
6.5 InSb Quantum Dots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
6.5.1 Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
6.5.2 Structural Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
6.5.3 Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
6.5.4 Current – Voltage Characteristics . . . . . . . . . . . . . . . . . . . 126
6.5.5 Electroluminescence . . . . . . . . . . . . . . . . . . . . . . . . . . 126
6.5.6 Power and Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . 129
6.5.7 Inclusion of AlGaSb Barriers . . . . . . . . . . . . . . . . . . . . . 130
6.5.8 Growth on GaSb . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
6.5.9 Comparison of Quantum Dot Samples . . . . . . . . . . . . . . . . 141
6.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
7 Conclusions and Suggestions for Further Work 147
7.1 Summary of Achievements . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
7.2 GaInSb/(Al)GaSb Quantum Wells . . . . . . . . . . . . . . . . . . . . . . 149
7.2.1 Suggestions for Future Work . . . . . . . . . . . . . . . . . . . . . 149
7.3 InAs Quantum Dashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
7.3.1 Suggestions for Further Work . . . . . . . . . . . . . . . . . . . . . 151
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